From cd443f1e91ca600a092e780e8250cd6a2954b763 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Thu, 18 Jan 2018 14:48:03 +0800 Subject: [PATCH] netlink: reset extack earlier in netlink_rcv_skb Move up the extack reset/initialization in netlink_rcv_skb, so that those 'goto ack' will not skip it. Otherwise, later on netlink_ack may use the uninitialized extack and cause kernel crash. Fixes: cbbdf8433a5f ("netlink: extack needs to be reset each time through loop") Reported-by: syzbot+03bee3680a37466775e7@syzkaller.appspotmail.com Signed-off-by: Xin Long Acked-by: David Ahern Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 47ef2d8683d6cf..84a4e4c3be4b97 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2391,6 +2391,7 @@ int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *, while (skb->len >= nlmsg_total_size(0)) { int msglen; + memset(&extack, 0, sizeof(extack)); nlh = nlmsg_hdr(skb); err = 0; @@ -2405,7 +2406,6 @@ int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *, if (nlh->nlmsg_type < NLMSG_MIN_TYPE) goto ack; - memset(&extack, 0, sizeof(extack)); err = cb(skb, nlh, &extack); if (err == -EINTR) goto skip;